Installing a tub

Putting in a bathtub for my daughter, house is 60 years old at least. Floor from wall is out of level by about 3/4" in the 5 foot area where the tub will sit. How should I level the floor and what would you use. If I had the time and money I'd like to see the center beam jacked up but i don't. House is a old balloon framed house, one story with full basement with a very low ceiling. Wish I had my camera with me. Any and all help is welcomed.

IF it is out of level in that direction, it must mean the joists are parallel to the front of the tub, so you cannot recess the tub into the sub floor and let the high end rest on the joists. Therefore, your only solution may be to level the tub after setting it on the subfloor and then raising the floor 3/4" to close the gap at the low end.

IF it is out of level in that direction, it must mean the joists are parallel to the front of the tub, so you cannot recess the tub into the sub floor and let the high end rest on the joists. Therefore, your only solution may be to level the tub after setting it on the subfloor and then raising the floor 3/4" to close the gap at the low end.

Leveling the tub is important for proper draining, and keeping water from pooling, and maybe end up rotting things because they stay damp.

My whole downstairs was unlevel, and I went the route of stripping all of the subflooring off, planing and shimming the joists, then installing new subflooring. it was a major effort, but with the use of a laser level and time, the whole floor is level to within about 1/8" across the full surface.

If you strip the subflooring off, you could sister new joist segments onto them that are now level, then put new subflooring down on the sisters. this would make installation of the tub, vanity, toilet, and tile, if desired, in the remodel project much easier. the biggest problem comes in a big transition out of the bathroom into the hallway. I redid my upstairs bathroom, and installed pex in a pretty thick bed of slc for radiant heat. this raised the floor easily 1.5", and I don't find the transition to the hallway a problem. I happened to have some stone saddles made that matched the granite counter, but it could also be done with wood or other materials.

If you can live with just the tub level, you could set it in a mortar mix, or choose stuctolite.

To install that over a wooden floor, you'd need to install the special primer, staple down some metal lath, then pour the stuff on. It also requires that you had previously installed a layer of sil wrap or something around the perimeter to provide an expansion joint and seal any edges or holes to ensure the stuff doesn't flow out the door and down any holes.

A less expensive choice, that would need to be thicker, is to do a mudpack floor. this needs to be at least 1.25" thick, though. SLC over wood should be around 1/2" thick at the thinnest (peak) location. Some can be applied thinner, and can be feathered to zero over concrete, but not over wood...it would not have enough strength.

SLC is neat suff; expensive, but once the prep is done, and it's done properly, makes a perfectly flat and level floor in little more time than it takes to mix and pour the stuff. You need a paddle or rake to move it around (think pancake batter), but once you do that, and get it deep enough, just like pouring water into a glass, it will be level. You have to mix and pour quick, because it starts to set up in often 10-minutes or so from when it first hits water to start to mix it. You can walk on it and start to set tile later the same day with most.